I had this problem last year or so with an e28. Two weeks on that one.

After your mini vacation:
-FULLY recharge the battery.
-Check and clean all engine compartment grounds. Battery to body, battery to block, motor mount to chassis and for some extra measure add one from the valve cover to the chassis (my 86 535 has one from the rear of the valve cover to the firewall).
-Pull the plugs out, clean them off.
-Either let the cylinders dry out (if raw gas smell), or just reinstall the plugs (if no raw gas).
-Check the cap and rotor condition.
-Check the fuel pressure, just because the pump is running, doesn't mean it's running properly.
-Check and measure the AFM connections. Make sure the flapper door swings freely.
-Check and measure the coil posts.
-Coil wire to cap good?
-The O2 sensor doesn't matter for now. My parts cars sensor is completely gone, just the downpipes are left of the exhaust, it started right up (after I reinstalled the OBC relay box).
-Pinch off the cold start fuel line (careful of puncturing it though, you don't want to replace that unless necessary).
-The car does have gas and that gas is good correct?
-Last resort, borrow a good ECU.

I haven't read through the posts again, but did you try jumping the 11 and 14 pins on the diagnostic connector? * Car in Park, pay attention to the orientation of the pins numbers-backwards to the cap.

I gave up for a day or two, came back, worked on it some more and it started. Has been going since. Keep the faith.

• 15 second start...then kill 1984 733i (pic) - weierj80 2008-04-13 17:38:50 (218 views)
  • update: 15 second start...then kill 1984 733i (pic) - weierj80 2008-04-13 19:12:54 (161 views)
    • Maybe some pics to help- (pic) - stevebu 2008-04-13 20:33:59 (152 views)
      • Re: Maybe some pics to help- - weierj80 2008-04-15 11:04:05 (72 views)
      • Re: Maybe some pics to help- - weierj80 2008-04-15 09:59:32 (75 views)
      • And the all important main relay- (pic) - stevebu 2008-04-13 20:38:08 (124 views)
        • I give up... - weierj80 2008-04-20 18:22:18 (67 views)
          • Take a day off and don't think about it-seriously. - stevebu 2008-04-20 21:46:55 (73 views)
            • Re: Take a day off and don't think about it-seriously. - weierj80 2008-04-20 22:50:56 (58 views)
              • The latest bit. - weierj80 2008-04-27 15:42:59 (69 views)
                • Re: The latest bit, correction. - weierj80 2008-04-27 16:01:38 (62 views)
                  • This is how the 83 I have is: - stevebu 2008-04-28 16:19:48 (59 views)
    • im not positive, but i think it is the valve for the (url) - goms187 2008-04-13 19:25:09 (105 views)
      • Re: im not positive, but i think it is the valve for the - weierj80 2008-04-13 19:35:42 (75 views)
        • no dice - weierj80 2008-04-13 20:11:20 (78 views)
          • Re: no dice - goms187 2008-04-13 20:37:56 (74 views)
            • Re: no dice - weierj80 2008-04-13 23:46:12 (69 views)